Liquid toners for electrostatic printing



United States Patent Ofice 3,542,682 Patented Nov. 24, 1970 US. Cl.252-621 9 Claims ABSTRACT OF THE DISCLOSURE A positive-working liquidtoner composition comprising in an electrically insulating carrierliquid, a pigment, e.g. carbon black, a metal soap and a dispersingagent comprising an alkylated polymer of a heterocyclic N- vinylmonomer.

The present invention relates to a liquid toner composition for use inelectrostatic printing processes; more particularly, the presentinvention relates to a positiveworking liquid toner system comprising inaddition to an electrically conductive carrier liquid, a pigment, and ametal soap, a dispersant comprising an alkylated polymer of aheterocyclic N-vinyl monomer.

Although a great number of liquid toner compositions or systems for usein electrostatic printing processes have been disclosed in theliterature, many of such compositions or systems have not been foundcompletely satisfactory in view of their inability to remain insuspension adequately or to give copies which have uniform fill and arefree from bleeding or similar streaking characteristics.

With respect to electrophotographic processes in general, it is knownthat various liquid developing agents or toners are capable of producingelectrophotographic images on photoconductive surfaces in variouscolors. Thus, for example, if the photoconductive surface comprises zincoxide, which substance is not capable of supporting a positiveelectrostatic charge, it is necessary for the developer particlessuspended in a liquid carrier to assume positive polarity with respectto the latent electrostatic image formed on the zinc oxide surface. Thisis because the latent image formed on the zinc oxide surface can beformed essentially by a negative electrostatic charge only. Accordingly,there has been a great desire for the production of a positive-workingelectrostatic developer or toner composition or system which thepositive-Working polarity characteristics so as to effect the necessarydevelopment of the latent image on the zinc oxide or similar surface yetwill be free of the inherent deficiencies of non-uniformity and bleedingand streaking characteristics associated with the employment ofpreviously utilized materials.

It has now been found in accordance with the present invention thatexcellent, positive-working electrostatic toners free from thedisadvantages and deficiencies of prior art materials, i.e. theirability to remain in suspension and give copies having uniform fill andfree from bleeding and streaking characteristics are provided by asystem comprising in an electrically insulating carrier liquid, acoloring agent, a metal soap, and a dispersing agent comprising analkylated polymer of a heterocyclic N-vinyl monomer.

Accordingly, it is a principal object of the present invention toprovide a positive-working electrostatic toner or developer free fromthe inherent deficiencies and disadvantages of prior art compositions orsystems.

A further object of the present invention comprises a positive-workingelectrostatic toner containing in an electrically insulating carrierliquid a coloring agent, a metal soap, and a dispersing agent.

A still further object of the present invention comprises a new andimproved liquid electrostatic toner having an improved ability to remainin suspension and yielding uniform prints and copies free from bleedingand streaking characteristics comprising in an electrically insulatingcarrier liquid a colorng agent, e.g. carbon black, a metal soap and adispersing agent comprising an alkylated polymer of a heterocyclic'N-vinyl monomer.

Still further objects and advantages of the novel liquid toner systemsof the present invention will become more apparent from the followingmore detailed description thereof.

The above objects and advantages of the present invention are providedby a liquid positive-working electrostatic toner comprising anelectrically insulating carrier liquid containing a coloring agent, e.g.carbon black, a metal-organic salt or soap and a dispersing agentcomprising an alkylated polymer of a heterocyclic N-vinyl monomer.

Thus, while various metal-organic salts have been described in thepreparation of liquid toners as charge agents or drying agents, e.g. US.Pat. 3,259,581, it has been discovered in accordance with the presentinvention that the use of certain metal salts or soaps in combinationwith a dispersant comprising an alkylated polymer of a heterocyclicN-vinyl monomer in an electrically insulating carrier liquid containinga dispersed pigment or dye that a liquid electrostatic toner isproduced, which toner does not suffer from an inability to remain insuspension or a failure to provide a uniform fill and a copy free frombleeding and streaking characteristics such as associated with prior artsystems. In this respect, it has now been discovered in accordance withthe present invention that certain liquid toner systems containingcertain metal soaps even in amounts less than 1% by weight are extremelyefiective positive-Working toner systems when a dispersant isincorporated within the system comprising an alkylated polymer of aheterocyclic N-vinyl monomer. It is pointed out that the use of suchdispersant alone in a liquid toner system absent the employment of themetal soap provides a negative-working electrostatic toner, andaccordingly, it is surprising that an exceptionally positive-workingtoner eliminating the inherent deficiencies and disadvantages of theprior art is provided by the employment of the combination of theparticular metal soaps and dispersing agents in accordance with thepresent invention.

Thus, in accordance with the present invention the liquid tonercomposition or system comprises as a base iluid any of the conventionalelectrically insulating carrier liquids generally employed in liquiddeveloper and toner compositions. Such electrically insulating carrierliquids generally comprise hydrocarbon solvent materials having thenecessary di-electric constant, e.g. less than 3 and volume resistivity,e.g. in excess of 10 ohm centimeter so as to be acceptably employed inthe electrostatic reproduction process. Thus, for example the solventcan comprise various hydrocarbon solvents, e.g. toluene, kerosene andmixtures thereof as well as various commercial petroleum and hydrocarbonsolvents, e.g. Isopar having a boiling range of from ISO-182 C. orSolvesso having a boiling range of from -174 0., Shell X4 having aboiling range of from 58-70 C., or Shell X55 having a boiling range offrom 58140 C., can be effectively employed as the electricallyinsulating carrier liquid of the liquid toner system.

The coloring agent or pigment employed in accordance with the liquidelectrostatic toner of the present invention can again comprise any ofthose conventionally employed in such conventional electrostatic toners.Thus, for example, the coloring agent or pigment can comprise carbonblack, channel black, alkali blue, nigrosine dyes,

3 etc. In this respect, any conventional coloring agent or pigment whichis dispersible in the carrier liquid can be employed in the liquidelectrostatic toner of the present invention.

The pigment, e.g. carbon black suspended in the carrier liquid as thetoner is employed in that amount necessary when attracted to thenegative electrostatic lmage through the positive-working of the metalsoap and dispersing agent in the toner system to be deposited on theimage areas only and provide the desired positive print or copy.Generally, the pigment comprises from about .001% to about of the tonersystem or composition. Of course, slightly lesser or greater amounts canbe employed where desired for particular purposes.

Since the pigments would by themselves in the insulating carrier liquidassume fully or partially negative polarity in respect to the negativeelectrostatic latent image, such pigments would tend to deposit onto thenon-image areas to a greater or lesser degree or would deposit both ontothe image and non-image areas. For this reason, therefore, it isnecessary to modify the characteristics of the pigmented insulatedcarrier liquid so as to provide a positive-working system wherein thepigment particles. are deposited only onto the image areas of thenegative electrostatic latent image by assuming a positive electrostaticcharge. This is accomplished in accordance with the present invention byincluding within the pigmented electrically insulated carrier liquidboth a metal soap which tends to be absorbed on the pigment particlesurfaces, and an alkylated polymer of a heterocyclic N-vinyl monomer,which as a dispersing agent provides a uniform dispersion of the tonerso as to allow the production of a copy having a uniform fill and freefrom bleeding or streaking characteristics not heretofore attainable byprior art systems. The metal soaps or salts employed in accordance withthe present invention are the hydrocarbon solvent soluble salts of themetals cerium, iron, nickel, cobalt, zirconium, cadmium, lithium,magnesium, manganese, calcium, barium, strontium, chromium and indium,the salts or soaps of such metals in the liquid toner system of thepresent invention providing copies having no tendency to bleed orstreak. The use of salts of lead, zinc or antimony, for example, tend togive relatively poor copies. Accordingly, the salts or soaps of thesemetals are not preferably employed in accordance with the presentinvention.

As indicated previously, the salts or soaps generally employed inaccordance with the present invention are those which are soluble in thecarrier liquid which is generally a hydrocarbon fraction. In thisrespect, suitable soaps include the metal linoleates, naphthenates,resinates, palmetates, stearates, oleates, octoates, etc.

In accordance with the present invention, alkylated polymers ofheterocyclic N-vinyl monomers are utilized as the dispersants. Thesedispersants are those prepared by alkylation of a homopolymer orcopolymer of a heterocyclic N-vinyl monomer, preferably an N-vinyllactam monomer and most preferably an N-vinyl pyrrolidone monomer withan alpha-olefin containing from 2 carbon atoms to 2000 carbon atoms,preferably in the range of from 2 to 200 carbon atoms, and mostpreferably in the range of from 8 to 42 carbon atoms, said alkylationprocess being more fully described in General Aniline & FilmCorporations co-pending patent application, Ser. No. 508,547, filed Nov.18, 1965 and now U.S. Pat. No. 3,417,054, or by simultaneouslypolymerizing and alkylating a mixture containing a heterocyclic N-vinylmonomer, a monoethylenically unsaturated polymerizable monomer and analpha-olefin containing from 2 carbon atoms to 2000 carbon atoms or amixture of the same or two different heterocyclic N-vinyl monomers andan alphaolefin containing from 2 carbon atoms to 2000 carbon atoms, saidsimultaneous polymerization and alkylation process being more fullydescribed in General Aniline &

4 Film Corporations co-pending patent application, Ser. No. 525,374,filed Feb. 7, 1966 and now U.S. Pat. No. 3,423,367.

As examples of heterocyclic N-vinyl monomers which contain a carbonylfunction adjacent to the nitrogen in the heterocyclic moiety, whosealkylated polymer derivatives produced as described in saidapplications, Ser. Nos. 508,547 and 525,374, may be employed inpracticing the present invention, that may be mentioned are N-vinylsuccinimide, N-vinyl diglycolylimide, N-vinyl glutarimide,N-vinyl-3-morpholinone, N-vinyl-S-methyl 3-morpholinone,N-vinyl-5-ethyl-3-morpholinone, N-vinyl oxazolidone, etc., and N-vinylring-oxygenated lactams as disclosed in U.S. Pat. 3,231,548, andespecially the N-vinyl 5-, 6- and 7-membered lactams, particularly N-vinyl pyrrolidone, characterized by the following formula:

wherein R and R are selected from the group consisting of hydrogen,methyl and ethyl, n is an integer of from 1 to 3, and m represents theaverage molecular weight as determined by relative viscositymeasurements which are designated as K values.

The viscosity coefiicient, K, which is fully described in ModernPlastics, vol. 23, No. 3, pp. 157-61, 212, 214, 216 and 218 (1945) iscalculated as follows:

log 71" l 751(0 where c is the concentration in grams per ml. of polymerin solution and the 1 is the viscosity of the solution compared tosolvent.

There may also be used the alkylated polymers of comparable monomers ofN-vinyl 5-, 6- and 7-membered thiolactams, N-acryloylpyrrolidone,-piperidone and -caprolactam; N-acryloyl 5 methyl-pyrrolidone,N-acryloyl-6- methyl piperidone and N-acryloyl-7-methyl caprolactam andtheir corresponding 5-, 6- and 7-ethyl derivatives;N-acryloxy-methyl-pyrrolidone, -piperidone and -caprolactam;N-methacryloxy ethyl-pyrrolidone, -piperidione and -caprolactam;N-methacryloxy-methyl-5-methyl pyrrolidone, -6-methyl-piperidone and-7-methyl-caprolactam; N-methacrylamido-methyh, N-methacrylamidoethyl-,N-methacrylamidopropyland N-(N-phenylacrylamidopropyl)-pyrrolidones,-piperidones and caprolactams.

The homopolymers of the N-vinyl lactams characterized by the foregoingformula (whose alkylated derivatives obtained, for example, as describedin said application Ser. No. 508,547, are suitable for use in practicingthe present invention) are readily obtained by homopolymerizing N-vinylpyrrolidone; N-vinyl-5-methyl pyrrolidone; N-vinyl-S-ethyl pyrrolidone;N-vinyl-5,5-dimethyl pyrrolidone; N-vinyl-5,5-diethyl pyrrolidone andN-vinyl-S-methyl-S-ethyl pyrrolidone; N-vinyl piperidone;N-vinyl-6-methyl piperidone; N-vinyl-6-ethyl piperidone;N-vinyl-6,6-dimethyl piperidone; N-vinyl-6,6-diethyl piperidone andN-vinyl-6-methyl-6-ethyl piperidone; N- vinyl caprolactam,N-vinyl-7-methyl caprolactam; N-vinyl- 7,7-dimethyl caprolactam;N-vinyl-7-ethyl caprolactam; N-vinyl-7,7-diethyl caprolactam andN-vinyl-7-methyl-7- ethyl caprolactam.

For the purpose of the present invention I employ alkylated derivativesof homopolymers of heterocyclic N- vinyl monomers having a K value fromabout 10 to 140, preferably from about 30 to 100. These homopolymers arereadily obtained by conventional homopolymerization procedures of theforegoing heterocyclic N-vinyl monomers described in U.S. Pats.2,265,450; 2,3l7,804; 2,335,- 454 and many others too numerous tomention in which working examples are given.

Copolymers obtained by copolymerizing to 99 mole percent of theforegoing heterocyclic N-vinyl monomers with 1 to 95 mole percent of amonoethylenically unsaturated polymerizable monomer and having a K valuefrom about to 140 are readily alkylated in accordance with the presentinvention to yield products having solubility characteristics dictatedby the end use.

The various monoethylenically unsaturated polymerizable monomers, whichare copolymerized with any one of the aforementioned heterocyclicN-vinyl monomers in the conventional manner and which will yieldcopolymers that are readily alkylated in accordance with saidapplication, Ser. No. 508,547, to produce alkylated copolymers suitablefor use in practicing the present invention, include vinyl esters suchas vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate,vinyl lactate, vinyl caproate, vinyl caprylate, vinyl oleate and vinylstearate; acrylonitrile; vinyl ketones; vinyl cyclohexane; styrene;2-vinyl pyridine, 4-vinyl pyridine; acrylic acid, acrylate estermonomers of the formula:

CH =CHCOOR wherein R represents either a straight or branched alkyl offrom 1 to 18 carbon atoms or an alkoxyalkyl in which the total number ofcarbon atoms in the alkyl groups range from 3 to 6.

As examples of such acrylate esters the following are illustrative:methyl, ethyl, propyl, isopropyl, butyl, isobutyl, s-butyl,Z-methyl-l-butyl, 3-methyl-1-butyl, 2-ethyll-butyl, amyl, 3-pentyl,Z-methyl-l-pentyl, 4-methyl-2- pentyl, hexyl, 2-ethyl-hexyl, heptyl,2-heptyl, octyl, 2-octyl, nonyl, 5-ethyl-2-nonyl, decyl,2-methyl-7-ethyl-4-undecyl, dodecyl, tetradecyl, hexadecyl, octadecyl,2-methoxyethyl, 2-ethoxyethyl and 2-butoxyethyl acrylate; methacrylicmonomers such as methacrylic acid, methyl methacrylate, cyclohexylmethacrylate, isobutyl methacrylate, isoamyl methacrylate, fl-methoxyethyl methacrylate and a-(o-chlorophenyl) ethyl methacrylate, B- phenoxyethyl methacrylate, a-phenyl ethyl methacrylate, phenyl methacrylate,o-cresol methacrylate, p-cyclohexylphenyl methacrylate, 2-nitro-2-methylpropyl methacrylate, diethylamino-ethylmethacrylate, ethylidene acetatemethacrylate and glycidyl methacrylate, including esters of halo acrylicacids, such as methyl-2-chloro-acrylate, ethyl-a-chloro-acrylate,phenyl-u-chloroacrylate, tar-ethylacrylic acid; methacrylonitrile;N-alkyl and N-aryl substituted acrylamides such as N-methyl acrylamide,N- ethyl acrylamide, N-propyl acrylamide, N-n-butyl acrylamide,N-n-dodecyl acrylamide, N-n-octadecyl acrylamide, N,N-dimethylacrylamide, N,N-diethyl acrylamide, N-N-di-n-butyl acrylamide,N-N-di-isobutyl acrylamide, N-cyclohexyl acrylamide, N-N-dicyclohexylacrylamide, N-phenyl acrylamide, N-p-nitro-phenyl acrylamide,N-anaphthyl acrylamide, N-fi-naphthyl acrylamide, N-methyl-N-phenylacrylamide, N,N-diphenyl acrylamide, N- benzyl acrylamide, N,N-di-benzylacrylamide; and grafted monomers of the type disclosed in US. Pats.3,029,219; 3,035,009; 2,036,033 and the like.

A mixture consisting of from 5 to 99 mole percent of any one of theforegoing heterocyclic N-vinyl monomers and from 1 to 95 mole percent ofa different heterocyclic N-vinyl monomers, such as for example, N-vinyllactam with either N-vinyl succinimide, N-vinyl-3-morpholinone, and thelike, may also be copolymerized and the resulting copolymer alkylatedfor use in the present invention.

From numerous experiments connected with the present invention, it hasbeen found that the configuration of the foregoing monoethylenicallyunsaturated monomers, and numerous others, is immaterial since they allcopolymerize in the aforementioned proportions with the heterocyclicN-vinyl monomers and yield copolymers which are soluble in the organicsolvent or mixture thereof and which are readily alkylated.

With regard to the u-olefins employed for producing the alkylatedpolymers used in practicing this invention, it is to be noted at theoutset that any a-olefins having a molecular weight from about 28 to ashigh as about 28,000, may be employed as the alkylating agent for thealkylated polymers of the various heterocyclic N-vinyl monomers. Asexamples of such a-olefins, the following are illustrative: ethylene,propylene, l-butene, l-pentene, 2-ethyl-1-butene, 2-methyl-l-pentene,l-hexane, 5-methyl-l-hexene, 2-methyl-l-pentene, 3-ethyl-1-pentene,l-heptene, l-octene, l-nonene, 2-ethyl-l-hexene, l-decone, 1- dodecone,l-tetradecene, l-hexadecene, l-heptadecene, loctadecene, l-nonadecene,l-eicosene, l-docosene, l-tetracosene, l-pentacosene and polybutenes ofmolecular weight of 400 to 2500 may be employed.

While linear u-olefins are preferred because of their commercialavailability, numerous isomers of a-olefins ranging from l-pentene tol-pentacosene as well as polybutenes may also be employed in thealkylation reaction. The only requirement in such case is that theisomer contained in ethylenic unsaturation in the a-position thereof.

Instead of employing any of the foregoing individual a-olefins, amixture of commercially available linear ocolefins produced by crackingpetroleum wax or by polymerizing lower olefins may also be used as thealkylating agent. Alpha-olefins in the carbon range of from C -C C -C CC11; C -C and C -C are commercially available and may be used. A mixtureof a-olefins containing from 65 to percent of a-olefins of from C to Ccarbon atoms having an average molecular weight of 366 is alsocommercially available and such mixture is employed in the alkylationreaction.

The quantity of the alkylated polymers of the heterocyclicN-monomonomers employed for a given amount of pigment or coloring agentis not critical in accordance with the present invention, suchdispersing agent need only be employed in that amount sufficient toprovide a stable suspension or dispersion of the pigment. Generally, thedispersing agent is employed in the range of 0.01 to 2-3 times theweight of the pigment, and preferably within the range of 1 to parts per100 parts of the pigment employed.

The dispersing agents employed in accordance with the present inventionact to provide a stable, uniform dispersion of the pigment particleswithin the liquid electrostatic toner system so as to provide a copyhaving a uni form fill and free from bleeding or streakingcharacteristics. It is theorized that the salts or soaps employed impart strong, electrical charges to the toner or pigment particles bybeing absorbed on the particle surfaces thus causing the particles to bedrawn to the sensitized paper with suflicient attraction to firmly fixthe particles on the image. Since excessive amounts of the metal saltsor soaps tend to result in weak images, a fact possibly explained inthat the organic salt or soap molecules themselves are drawn to thepaper surface and thus satisfy the electrical charge of the area withoutimparting a color at that point, it is generally disadvantageous toemploy more than about 3% by weight of the metal salts or soaps.However, in contradistinction to that set forth in US. Pat. 3,259,581wherein it is disclosed at least 1% of metal based on the pigment isrequired it has been found in accordance with the present invention thatthe salt concentration can be considerably lower than this prior artrecognized lower limit. In this respect, in accordance with the presentinvention, when employing a dispersing agent comprising an alkylatedpolymer of a heterocyclic N-vinyl monomer it is possible to employ ametal soap in an amount ranging from about 0.5% to about 3% by weight.Again, the beneficial results associated with the present invention,i.e. the production of copies having uniform fill and free from bleedingor streaking characteristics is associated with the combined employmentof the metal soap or salt and the dispersing agent comprising thealkylated polymer of a heterocyclic N-vinyl monomer.

In accordance with the present invention, the manner by which thedispersion is produced is in no way critical. In this respect, it hasbeen found that 3-roll mill, ball mills, colloid mills, high speed shearmixers, etc., are all applicable in the production of the dispersionsemployed in the liquid electrostatic toner systems of the presentinvention. In addition, as used throughout the instant specification andin the appending claims the expression coloring agent is meant toembrace all and any pigments and dyestuffs applicably employed in thepresent and like electrostatic liquid toner systems. Thus, for example,such term embraces carbon blacks including furnace blacks, lamp blacks,channel blacks and other black materials made by processes well known inthe art. Similarly embraced are colored pigments including thephosphotungstate and phosphomolybdate colors, alkali blue and many azopigments as well as nigrosine dyestuffs and triphenylmethine dyes inparticular. Of course, any and all pigments and dyestuifs capable ofyielding color copies when attracted to the negative latent image by theaction of the metal soaps and dispersing agents can be advantageouslyemployed.

The present invention will now be described by reference to thefollowing specific examples. It is to be understood that such examplesare presented for purposes of illustration only, and the presentinvention is in no way to be deemed as limited thereo.

EXAMPLE I The following materials were mixed on a 3-roll mill to obtaina uniform dispersion as a heavy ink.

1 On olefin-alkylated polyvinylpyrrolidone of an average olefin carbonchain length of 16 carbon atoms and 20% vinylpyrrolidone residue.

-An aliphatic petroleum solvent having a boiling range of The ink wasadjusted to carbon black content with additional Isopar M. Then 7 cc. ofthe 5% toner was added to 1 liter of additional aliphatic petroleumsolvent to produce the final liquid toner system.

Prior to use in an electrostatic reproduction process a few drops of thefollowing solutions were added; when employed in an SCM-33 copier,resulted in excellent copies of uniform fill and no streaking orbleeding characteristics.

Cerium naphthanate (0.6%) 1 Strontium naphthenate (0.6%) Chromiumnaphthenate (0.6%) Indium naphthenate (0.6%) Nickel octoate (1.0%)Zirconium octoate 0.6%) Cadmium octoate (1.6%) Magnesium naphthenate(1%) Manganese naphthenate (0.6%) Barium octoate (0.6%)

1 Approximate metal content of toner.

EXAMPLE II The following materials were charged to a ball mill.

G. Carbon black 2O Ganex 220 1 20 Isopar M 370 Zirconium octoate (6%) 51 An olefin alkylated polyvinylpyrrolidone of an araryl olefin length of20 carbon atoms and 20% vinylpyrrolidone residue.

This toner when tested at a concentration of about 6 cc.

per liter of aliphatic petroleum solvent gave excellent pr1nts.

8 EXAMPLE III The following materials were mixed and passed over a3-roller mill to make an ink. The concentration of Spirit Nigrosine wasadjusted to about 5% by mixing the above ink with additional petroleumsolvent.

G. Spirit Nigrosine 10 Ganex 216 5 Isopar M 5 This 5% toner when testedhad a charge opposite to that needed. However, by adding a few drops ofZr octoate (0.6% Zr) an excellent toner with proper polarity resulted.Again, copies of uniform fill without any tendency to bleed or streakresulted.

EXAMPLE IV This mixture was then mixed with Zr octoate at a ratio ofabout 25 cc. of toner to 1 cc. of 6% (Zr) octoate solution.

This mixture when tested gave excellent blue prints.

EXAMPLE V The following materials were mixed and passed over a 3-rollermill to make an ink. The ink was adjusted to 5% pigment concentrationwith additional petroleum solvent.

Gms. 15 7.5 27.5

When 10 cc. of the above was mixed with 2 cc. of zirconium octoatesolution, a toner that gave excellent prints resulted.

While the present invention has been described primarily with respect tothe foregoing specific examples, it is to be understood that the presentinvention is in no way to be deemed as limited thereto, but must be comstrued as broadly as all or any equivalents thereof.

I claim:

1. A positive working electrostatic liquid toner comprising (a) anelectrically insulating carrier liquid having a dielectric constant ofless than three and a volume resistivity in excess of 10 ohm centimeter;(b) a coloring agent dispersible in said carrier liquid and capable ofyielding color copies when attracted to a negative latent image; (c) ametal soap of a fatty acid soluble in said carrier liquid; and (d) as adispersant for said coloring agent an alkylated polymer of aheterocyclic N-vinyl monomer in which the alkyl radical of said polymercontains from 2 to 2000 carbon atoms, and said polymer has a K value ofabout 10 to 140.

2. The electrostatic liquid toner of claim 1 wherein said alkyl radicalof said polymer contains from 8 to 42 carbon atoms.

3. The electrostatic liquid toner of claim 2 wherein said alkylatedpolymer is an alkylated polymer of an N-vinyl pyrrolidone monomer.

4. The electrostatic liquid toner of claim 1 wherein said metal soapcomprises a soap selected from the group consisting of the linoleates,naphthenates, resinates, palmetates, stearates, oleates and octoates ofa metal selected from the group consisting of cerium, iron, nickel,cobalt, zirconium, cadmium, lithium, magnesium, manganese, calcium,barium, strontium, chromium and indium.

Pyrazolone Red B Ganex 220 Isopar M 5. The electrostatic liquid toner ofclaim 4 wherein said electrically insulating carrier liquid is ahydrosaid alkyl radical of said polymer contains from 8 to 42 carbon.carbon atoms. References Cited 6. The electrostatic liquid toner ofclaim 5 wherein I said alkylated polymer is an alkylate polymer of an N-UN TED PATENTS vinyl pyn-olidone monomen 5 3,231,374 1/ 1966 Sc1amb1252-621 7. The electrostatic liquid toner of claim 3 wherein 3,079,2702/1963 Cortez 252-621 said coloring agent comprises carbon black.

8. The electrostatic liquid toner of claim 6 wherein GEORGE LESMESPnmary Exammer said coloring agent comprises carbon black. 10 I. P.BRAMMER, Assistant Examiner 9. The electrostatic liquid toner of claim 1wherein

